Methods for Automatic Groove Identificatoin in 3D Bullet Land Scans
Kiegan Rice
Methods for Automatic Groove Identification
in 3D Bullet Land Scans
Kiegan Rice
Iowa State University
August 2nd, 2018
Background: Statistics Applied to Forensic Science
Validity of forensic evidence analysis has come under fire in the last decade
2016 PCAST report on feature-comparison methods
NIST Center of Excellence established in 2016
Background: Bullet Lands
When a gun is fired, the bullet is propelled forward through the barrel
As it travels down the barrel, it makes contact with parts of the barrel
Striations result from this contact
Striations are observed on land engraved areas (
lands
). Lands are separated by groove engraved areas (
grooves
).
Background: Collection of Land Data
Sensofar Confocal Light Microscope
Hamby set 44 - 35 bullets from 10 consecutively rifled Ruger barrels
Rescanned with CSAFE’s microscope
To use as ‘base’ set; methods to be tested on several other data sets
Have manual groove identifications for this whole set
Each pixel: .645 square microns
Each land is 2mm (2000 microns) wide
A scan of one bullet (6 individual lands) takes ~1 hour
Background: Land Surface